FORD EXPLORER GAS PROBLEM

2000 Ford Explorer • 189,000 miles

Just replaced cyclinder heads, new gaskets, bolts, torque to specs w/ help from buddy. Assembled rest of car as required in manual, this is my 4th head job on ford 4.0 ohv, feel fairly knowledgeable. Start up runs terrible, rough as though a cyclinder is not firing. Checked coil spark to all cyclinders, replaced plugs and O2 sensors both banks. When replacing heads injectors were placed in gasoline and forgotten, sat for 2 weeks in petro. Showing codes p171 & p174, have checked can not find any vacume leaks, sprayed with brake cleaner, checked everywhere can not figure out any suggestions please thompsri69@gmail. Com